[ExI] Rocket lander control systems

[BillK]

On Mon, 4 Jan 2021 at 01:20, spike jones via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> Ja, but it comes down empty.
>
> We can do some ballpark figures in our heads.  Imagine a first stage, 4
> meters diameter, length 30 meters.  Agreed those dimensions would be
> suitable to support the upper stages during a 2 g launch event?
>
> OK, Lox is about the same density as water, a little higher, kerosene is
> lower than water, but you need less of it, so we can just use water density
> for BOTEC estimate.  Those dimensions return a fuel/oxidizer mass of about
> 400 tons.  A typical Lox/JP4 first stage has a ratio of about 1/11 range, so
> lets go with the heavy end, about 40 tons, which is about the mass of an
> empty Boeing 737.
>
> A single strand of that 3 cm diameter nylon cord is good for 15 tons.  Get
> several of them working together, they should be able to deal with the
> momentum of our 737 eqivalent.  If we can slow it down enough before impact
> with the net, we aughta be able to catch and suspend something of that mass.
>
> spike
> _______________________________________________


I don't think you appreciate just how big these things are!  :)

300 metric tons is the dry weight of Stage1 booster.
He wants to put about 3,000 metric tons of fuel in it.
The Stage2 Starship on top is not quite as big as that again, but it
goes to orbit.

I'm looking at some spaceX stats.
<http://spacelaunchreport.com/bfr.html>


BillK